Ink jet recording head and method of producing the same

ABSTRACT

Provided is an ink jet recording head, including: an ink ejection portion, in which heat is applied to ink supplied inside thereof, thereby providing the ink with a pressure for ejecting the ink outside; a substrate having a first surface on which the ink ejection portion is provided and a second surface on an opposite side to the first surface, the second surface having at least one recess; and a heat radiation member for releasing heat outside, the heat being transmitted from the ink ejection portion to the substrate, the heat radiation member having a protrusion with a shape corresponding to a shape of the recess, the protrusion being embedded in the recess so that the protrusion is provided in direct contact with the recess.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ink jet recording head for ejectingink through use of heat energy, and a method of producing the ink jetrecording head.

2. Description of the Related Art

Hitherto, an ink jet recording apparatus for ejecting ink to record animage on a recording medium is known. An ink jet recording head forejecting ink is mounted on the ink jet recording apparatus.

There is an ink jet recording head that includes an ink ejection portionfor ejecting an ink droplet through use of heat energy on a substrate.The ink ejection portion includes a heating resistor element forapplying heat to supplied ink to provide the ink with an ejectionpressure, and a nozzle plate provided with a nozzle for ejecting theink. A groove is formed in one side surface of the nozzle plate, and thenozzle plate is provided on the substrate so that the one side surfaceis held in abutment with the substrate. The groove and the substrateform an ink flow path.

The heating resistor element is placed at a position on the substratewhere the heating resistor element is capable of applying heat to inkstored in the ink flow path. When the heating resistor element generatesheat at a desired timing, the ink stored in the ink flow path is heated.The heated ink is boiled to generate a bubbling pressure, which allowsthe ink in the ink flow path to be ejected from the nozzle communicatingwith the ink flow path.

In such an ink jet recording head, the heat generated by the heatingresistor element may be transmitted also to the substrate, and thetemperature of the substrate may rise.

When the temperature of the substrate rises, the ink in the ink flowpath is heated by the heat of the substrate. That is, the ink is heatedeven in a state in which the heating resistor element does not generateheat, and the ink is boiled more easily. Thus, when the heating resistorelement generates heat, the heated ink is ejected in a period of timeshorter than that of ink not heated by the substrate. As a result, theink is ejected at a timing different from a desired timing, which causesa degradation in quality of a recorded image.

Further, the heat of the substrate may be transmitted to the nozzleplate, to thereby change the shape of the nozzle. The deformation of thenozzle may change the size of the ink droplet and an ejection directionthereof, and the ink droplet landing point deviates from a desiredposition to cause a degradation in quality of a recorded image.

Accordingly, Japanese Patent Application Laid-Open No. H04-144157discloses a structure in which a heat radiation member for releasingheat of a substrate is provided on the substrate. By releasing the heatof the substrate through the heat radiation member, an increase intemperature of the substrate can be suppressed, and hence the heating ofink by the substrate and the deformation of the nozzle can besuppressed. As a result, the degradation in quality of a recorded imagecan be suppressed.

However, in recent years, there has been a demand for an ink jetrecording head capable of recording an image with higher quality at ahigher speed.

In order to enhance image quality, an increase in density of the nozzleis effective, and along with this, it has been proposed that the heatingresistor elements be placed on the substrate at a higher density.Therefore, in such an ink jet recording head, a greater amount of heatcan be transmitted to the substrate more easily.

Further, in order to record an image at a higher speed, it has beenproposed that the interval between timings for the heating resistorelements to generate heat be shortened. In this case, the amount of theheat generated by the heating resistor elements per unit time becomeslarger.

By increasing the density of the arrangement of the heating resistorelements and shortening the interval between the timings for the heatingresistor elements to generate heat, in the structure disclosed byJapanese Patent Application Laid-Open No. H04-144157, the amount of theheat transmitted from the heating resistor elements to the substrate maybecome larger than that transmitted from the substrate to the heatradiation member in some cases. As a result, the heat of the substratemay not be released sufficiently, and the temperature of the substratemay rise, to thereby degrade recording quality.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an ink jet recordinghead having a higher heat radiation property, and a method of producingthe ink jet recording head.

In order to achieve the above-mentioned object, an ink jet recordinghead according to an aspect of the present invention includes: an inkejection portion, in which heat is applied to ink supplied insidethereof, thereby providing the ink with a pressure for ejecting the inkoutside; a substrate having a first surface on which the ink ejectionportion is provided and a second surface on an opposite side to thefirst surface, the second surface having at least one recess; and a heatradiation member for releasing heat outside, the heat being transmittedfrom the ink ejection portion to the substrate, the heat radiationmember having a protrusion with a shape corresponding to a shape of theat least one recess, the protrusion being embedded in the at least onerecess so that the protrusion is provided in direct contact with the atleast one recess.

Further, another aspect of the present invention relates to a method ofproducing an ink jet recording head including: an ink ejection portion,in which heat is applied to ink supplied inside thereof, therebyproviding the ink with a pressure for ejecting the ink outside; asubstrate having a first surface on which the ink ejection portion isprovided and a second surface on an opposite side to the first surface,the second surface having at least one recess; and a heat radiationmember for releasing heat outside, the heat being transmitted from theink ejection portion to the substrate, the heat radiation member havinga protrusion with a shape corresponding to a shape of the at least onerecess, the protrusion being embedded in the at least one recess so thatthe protrusion is provided in direct contact with the at least onerecess. In this aspect, the method includes: the step of forming the atleast one recess in the second surface of the substrate; and the step offorming the heat radiation member so that the heat radiation membercovers the second surface under a state in which a material for the heatradiation member fills the at least one recess.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are cross-sectional views of an ink jet recording headaccording to a first embodiment of the present invention.

FIGS. 2A, 2B 2C, 2D, 2E and 2F are cross-sectional views illustrating amethod of producing the ink jet recording head according to the firstembodiment of the present invention.

FIGS. 3A and 3B are cross-sectional views of an ink jet recording headaccording to a second embodiment of the present invention.

FIGS. 4A, 4B, 4C, 4D, 4E and 4F are cross-sectional views illustrating amethod of producing the ink jet recording head according to the secondembodiment of the present invention.

FIGS. 5A and 5B are cross-sectional views of an ink jet recording headaccording to a third embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an ink jet recording head and a method of producing the inkjet recording head according to the present invention are described indetail with reference to the drawings.

First Embodiment

FIGS. 1A and 1B are cross-sectional views of an ink jet recording headaccording to a first embodiment of the present invention. As illustratedin FIG. 1A, an ink jet recording head 1 includes an ink ejection portion2 in which heat is applied to ink supplied therein, thereby providingthe ink with a pressure for ejecting the ink outside, and a substrate 3having a first surface 3 a on which the ink ejection portion 2 isprovided.

FIG. 1A is a cross-sectional view taken along line 1A-1A in FIG. 1Bperpendicularly crossing the first surface 3 a of the substrate 3.Further, FIG. 1B is a cross-sectional view taken along line 1B-1B inFIG. 1A parallel to the first surface 3 a of the substrate 3.

The ink ejection portion 2 includes a heating resistor element 4 forapplying heat to ink to provide the ink with an ejection pressure, and anozzle plate 6 provided with a nozzle 5 for ejecting the ink. The nozzleplate 6 is provided on the first surface 3 a of the substrate 3. Asurface of the nozzle plate 6 on the substrate 3 side is provided with agroove, and the first surface 3 a of the substrate 3 and the groove forman ink flow path 7.

The heating resistor element 4 is provided on the substrate 3 so as tobe placed in the ink flow path 7 or in the vicinity thereof. The heatingresistor element 4 generates heat energy to heat ink in the ink flowpath 7. The heated ink is boiled and a bubbling pressure is generated inthe ink. The bubbling pressure functions as an ejection force of theink. The ink flow path 7 and the nozzle 5 communicate with each other,and the ink provided with the ejection force from the heating resistorelement 4 in the ink flow path 7 is ejected through the nozzle 5.

Further, in the ink jet recording head 1, a heat radiation member 8 madeof a material that has a heat conductivity higher than that of thesubstrate 3 and releases heat easily is provided on a second surface 3 bof the substrate 3. When the heating resistor element 4 generates heat,the heat is transmitted not only to the ink in the ink flow path 7 butalso to the substrate 3. The heat transmitted to the substrate 3 istransmitted to the heat radiation member 8, and is radiated outside ofthe ink jet recording head 1 (for example, atmosphere around the ink jetrecording head 1 or a component (not shown) provided in abutment withthe heat radiation member 8) from the heat radiation member 8.

The heat conductivity of the heat radiation member 8 is higher than thatof the substrate 3, and hence heat is released more easily to theoutside of the ink jet recording head 1 from the substrate 3, comparedwith an ink jet recording head having no heat radiation member 8. Morespecifically, the heat radiation member 8 can further suppress anincrease in temperature of the substrate 3 by the heating resistorelement 4 and prevent an increase in temperature of the ink by thesubstrate 3.

Further, by providing the heat radiation member 8 on the second surface3 b, the heat generated from the heating resistor element 4 can movemore easily toward the second surface 3 b. Thus, the movement of heatfrom the substrate 3 to the nozzle plate 6 provided on the first surface3 a is suppressed, which can prevent the nozzle 5 from being deformed byan increase in temperature of the nozzle plate 6.

Further, in a region, in which the heat radiation member 8 is provided,in the second surface 3 b of the substrate 3, at least one recess 9 isformed. Further, the heat radiation member 8 has a protrusion 10 havinga shape corresponding to the shape of the recess 9, and the heatradiation member 8 is joined to the second surface 3 b under a state inwhich the protrusion 10 is embedded in the recess 9. The protrusion isembedded in the recess so as to be in direct contact with the recess.Direct contact means that the protrusion and the recess are brought intocontact with each other with no adhesive or the like interposedtherebetween. Such a configuration can enhance a heat radiation propertyof the ink jet recording head 1. Further, the performance as a maskdescribed later is also enhanced.

Thus, the contact area of the substrate 3 and the heat radiation member8 is larger than that in a case where the substrate 3 and the heatradiation member 8 are provided in contact with each other at planeswithout unevenness, and heat is transmitted more easily from thesubstrate 3 to the heat radiation member 8. That is, the increase intemperature of the substrate 3 and the nozzle plate 6 can be furthersuppressed, and hence the increase in temperature of the ink by thesubstrate 3 and deformation of the nozzle 5 due to the increase intemperature of the nozzle plate 6 can be further prevented.

Note that, in this embodiment, the recess 9 has a hole shape, and theprotrusion 10 has a columnar shape matched with the hole shape. Needlessto say, the recess 9 and the protrusion 10 may have other shapes. Forexample, the recess 9 may have a groove shape, and the protrusion 10 mayhave a protrusion shape matched with the groove shape.

Further, ink supply paths 11 for supplying ink from outside of the inkjet recording head 1 (for example, an ink tank (not shown)) to the inkflow path 7 may be provided in the ink jet recording head 1 in such amanner as to pass through the substrate 3 and the heat radiation member8. Openings of the ink supply paths 11 formed in the second surface 3 band the ink tank (not shown) are connected to each other, to therebysupply ink from the ink tank to the ink flow path 7.

By using through-holes passing through the substrate 3 and the heatradiation member 8 as the ink supply paths 11, the ink jet recordinghead 1 having the ink supply paths 11 can be produced more easily with asmaller number of components.

Next, a method of producing the ink jet recording head 1 illustrated inFIGS. 1A and 1B is described with reference to FIGS. 2A to 2F. FIGS. 2Ato 2F are cross-sectional views illustrating the method of producing theink jet recording head 1.

Here, a production method is described in which a single crystal siliconwafer is used for the substrate 3, and the single crystal silicon waferis processed by dry etching using a mixed gas containing sulfurhexafluoride and oxygen to form the substrate 3. Note that, dependingupon the shape of the substrate 3, the single crystal silicon wafer maybe processed by dry etching using reactive ions, isotropic wet etching,or anisotropic wet etching.

First, as illustrated in FIG. 2A, the substrate 3 is prepared, whichincludes the heating resistor element 4, a mold 12 that is formed inregions to be the ink flow path 7 and the nozzle 5 (FIG. 1A), and thenozzle plate 6 on the first surface 3 a.

The heating resistor element 4, the mold 12, and the nozzle plate 6 canbe formed by a film formation method such as chemical vapor deposition(CVD) using plasma and sputtering vapor deposition. Further, etchingusing a photoresist mask can be applied for forming the heating resistorelement 4.

When the heating resistor element 4 and the mold 12 are formed, anetching stop layer (not shown) having an etching resistance property anda conductor (not shown) that transmits an electric signal to the heatingresistor element 4 may be formed on the first surface 3 a of thesubstrate 3.

It is desired that the etching stop layer be removed sufficiently slowlywith respect to the substrate 3 when the substrate 3 is processed by dryetching. Examples of a material for such an etching stop layer includealuminum and a silicon oxide. A removal agent of the etching stop layeris desirably removed faster with respect to the substrate 3, andexamples thereof include hydrofluoric acid and a phosphoric acid andnitric acid mixture.

For patterning the etching stop layer and the conductor, etching using aphotoresist mask can be applied.

Next, the process proceeds to a recess formation step of forming therecesses 9 in the second surface 3 b of the substrate 3 (FIG. 2B). Therecesses 9 are formed by forming, on the second surface 3 b, a resistpattern (not shown) having openings, and etching the second surface 3 b.The openings of the resist pattern are provided at positions where therecesses 9 are formed, and portions of the single crystal silicon waferat the openings are removed by etching to form the recesses 9. After therecesses 9 are formed, the resist pattern is peeled from the substrate3.

Subsequently, the process proceeds to a heat radiation member formationstep of forming the heat radiation member 8 on the second surface 3 b ofthe substrate 3 (FIG. 2C). At this time, the heat radiation member 8 isformed so as to cover the second surface 3 b under a state in which theheat radiation member 8 fills the recesses 9. By forming the heatradiation member 8 in this manner, the heat radiation member 8 havingthe protrusions 10 with a shape corresponding to the shape of therecesses 9 can be obtained relatively easily.

A surface 8 a of the heat radiation member 8 on an opposite side to thesubstrate 3 may have an uneven shape due to the shape of the secondsurface 3 b of the substrate 3, that is, due to the recesses 9. It ismore preferred that the surface 8 a of the heat radiation member 8 bepolished so as to be planarized.

As the material for the heat radiation member 8, a metal such as Au, Ta,Pt, or Ir having a heat conductivity higher than that of the singlecrystal silicon and having a relatively high ink resistance property, oralloys composed of at least two of these metals are desired. Further,when a metal such as Au is used, the heat radiation member 8 may beformed by electroplated coating so that the metal sufficiently fills theinside of each of the recesses 9. The plating thickness may be about 40μm to 70 μm.

When the heat radiation member 8 is formed, using the electroplatedcoating, a plating seed layer (not shown) may be formed on the secondsurface 3 b including inner surfaces of the recesses 9 so that the heatradiation member 8 is adhered to the substrate 3 relatively strongly.

As the plating seed layer, Ti/Au, TiW, Ti/Pd, or the like can be used.In a case of Ti/Au, it is desired that the film thickness be 2,000 Å forTi and 4,000 Å for Au. Needless to say, the film thickness is notlimited thereto.

Examples of a formation method for the plating seed layer include vapordeposition. When the vapor deposition is used, the angle of the secondsurface 3 b with respect to a deposition direction can be changed so asto form the plating seed layer on bottom surfaces and side surfaces ofthe recesses 9.

FIGS. 2D and 2E are cross-sectional views illustrating steps of formingthe ink supply paths 11 illustrated in FIGS. 1A and 1B. As illustratedin FIG. 2D, the heat radiation member 8 in regions to be the ink supplypaths 11 is removed to form a part of the ink supply paths 11 and toexpose the second surface 3 b at positions where the ink supply paths 11are to be formed. When Au is used for the heat radiation member 8, Aucan be removed by etching using an iodine-potassium iodide solution soas to form a part of the ink supply paths 11 in the heat radiationmember 8.

When the plating seed layer (not shown) is formed on the second surface3 b of the substrate 3, the plating seed layer in the regionscorresponding to the ink supply paths 11 is removed. When Ti/Au is usedfor the plating seed layer, the plating seed layer may be removed byetching using hydrogen peroxide.

Next, as illustrated in FIG. 2E, the substrate 3 in the regions to bethe ink supply paths 11 is removed to form the ink supply paths 11. Theink supply paths 11 can be formed by dry etching using CF-based reactiveions.

A metal such as Au is removed sufficiently slowly in dry etchingcompared with the single crystal silicon wafer. Thus, when the heatradiation member 8 is formed of a metal such as Au, the substrate 3 canbe processed by dry etching, using a remaining part of the heatradiation member 8 as an etching mask. By using the heat radiationmember 8 as the etching mask, a step of separately forming the etchingmask for dry etching can be omitted.

Subsequently, as illustrated in FIG. 2F, the mold (FIG. 2A) is removedto form the ink flow path 7 and the nozzle 5.

When the etching stop layer (not shown) is formed on the first surface 3a of the substrate 3 in the step of forming the heating resistor element4 and the mold 12 (FIG. 2A), the etching stop layer is removed beforeremoving the mold 12. When aluminum or a silicon oxide is used for theetching stop layer, the etching stop layer can be removed from the inksupply path 11 side by etching using hydrofluoric acid or a phosphoricacid and nitric acid mixture.

By providing the etching stop layer on the first surface 3 a of thesubstrate 3, the nozzle plate 6 can be prevented from being processed bydry etching when the ink supply paths 11 are formed. That is, the inkflow path 7 and the nozzle 5 can be formed with relatively highdimension accuracy.

The ink jet recording head 1 is completed by being separated from thesingle crystal silicon wafer with a dicer, if required.

The ink jet recording head 1 having the heating resistor elements 4placed at a higher density compared with that of a conventional examplewas produced, using the above-mentioned production method, and a testwas conducted in which recording was performed at a higher speed withrespect to a recording medium. As a result, recording was performed withhigher image quality. This is because the heat radiation property of theink jet recording head 1 during recording is enhanced.

The ink jet recording head 1 used in the test was produced as follows.

An etching stop layer (not shown) was formed on the first surface 3 a ofthe substrate 3 using aluminum, and a phosphoric acid and nitric acidmixture was used for etching of the etching stop layer. The substrate 3was etched by dry etching using a mixed gas containing sulfurhexafluoride and oxygen. Further, TiW was vapor-deposited on the secondsurface 3 b including the inner surfaces of the recesses 9 to form theplating seed layer (not shown).

In order to form the heat radiation member 8, a metal layer with athickness of 40 μm made of Au was formed on the second surface 3 b byelectroplated coating, and the surface of the metal layer was polishedso as to be planarized, to thereby form the heat radiation member 8.Through the planarization, the thickness of the heat radiation member 8from the second surface 3 b was set to be 5 μm.

In order to form the ink supply paths 11, portions of the heat radiationmember 8 were removed by etching using an iodine-potassium iodidesolution, and the plating seed layer was removed by etching usinghydrogen peroxide.

Second Embodiment

Next, an ink jet recording head according to a second embodiment of thepresent invention is described with reference to FIGS. 3A and 3B. FIGS.3A and 3B are cross-sectional views of the ink jet recording headaccording to the second embodiment. Description of the same componentsas those of the first embodiment is omitted.

As illustrated in FIG. 3A, the ink jet recording head 1 of thisembodiment includes a substrate 13 whose dimension in a path directionof the ink supply paths 11 (hereinafter, referred to as thickness)varies in one ink jet recording head 1. Specifically, a region of thesubstrate 13 in the vicinity where the ink supply paths 11 are formed(referred to as supply path formation region 14) is thinner than aregion of the substrate 13 other than the supply path formation region14, that is, a region where the ink supply paths 11 are not formed(referred to as supply path non-formation region 15).

Further, the ink jet recording head 1 according to this embodimentincludes the ink ejection portion 2 and the heat radiation member 8provided on the substrate 13 as in the first embodiment, and the inksupply paths 11 are formed so as to pass through the heat radiationmember 8 and the substrate 13.

FIG. 3A is a cross-sectional view taken along line 3A-3A in FIG. 3Bperpendicularly crossing a first surface 13 a of the substrate 13 onwhich the ink ejection portion 2 is provided. Further, FIG. 3B is across-sectional view taken along line 3B-3B in FIG. 3A parallel to thefirst surface 13 a of the substrate 13.

By setting the thickness of the supply path formation region 14 of thesubstrate 13 to be smaller, the path of each of the ink supply paths 11can be shortened. Thus, the fluid resistance in each of the ink supplypaths 11 can be decreased.

Further, by setting the thickness of the supply path non-formationregion 15 of the substrate 13 to be larger, the strength of the ink jetrecording head 1 can be increased. That is, a decrease in strength ofthe ink jet recording head 1 caused by the reduced thickness of thesupply path formation region 14 can be suppressed.

By setting the thickness of the supply path formation region 14 to besmaller, the heat capacity of the supply path formation region 14becomes smaller. Therefore, the temperature of the supply path formationregion 14 rises easily due to the heat from the ink ejection portion 2.

In view of this, in this embodiment, at least one recess 9 is formed ina second surface 13 b in the supply path formation region 14, and theradiation member 8 is joined to the second surface 13 b with theprotrusion 10 of the radiation member 8 embedded in the recess 9.

Thus, the contact area of the supply path formation region 14 and theheat radiation member 8 is larger than that in a case where the supplypath formation region 14 and the heat radiation member 8 are provided incontact with each other at planes without unevenness, and heat istransmitted more easily from the supply path formation region 14 to theheat radiation member 8. As a result, the increase in temperature of thesupply path formation region 14 due to the heat from the ink ejectionportion 2 is suppressed. Hence, an increase in temperature of ink by thesubstrate 13 and deformation of the nozzle 5 due to an increase intemperature of the nozzle plate 6 can be prevented, and thus, an imagewith higher quality can be recorded at a higher speed.

Further, in this embodiment, the path of each of the ink supply paths 11is shorter than that of the first embodiment and the fluid resistancethereof is smaller than that of the first embodiment. Therefore, ink canbe supplied to the ink ejection portion 2 more rapidly. Thus, recordingcan be performed at a higher speed.

The ink jet recording head 1 was produced with the thickness of thesubstrate 13 in the supply path formation region 14 being 100 μm and thethickness of the substrate 13 in the supply path non-formation region 15being 725 μm, and an image was recorded on a recording medium. As aresult, the image was recorded at a speed higher than that of aconventional example without allowing the quality of the recorded imageto be degraded.

Next, an example of a method of producing the ink jet recording head 1according to this embodiment is described with reference to FIGS. 4A to4F. FIGS. 4A to 4F are cross-sectional views illustrating the method ofproducing the ink jet recording head 1.

First, as illustrated in FIG. 4A, the substrate 13 is prepared, in whichthe heating resistor elements 4, the mold 12, and the nozzle plate 6 arelaminated on the first surface 13 a. When a single crystal silicon waferis used for the substrate 13, the substrate 13 is obtained by partiallyremoving, by etching, a region of the single crystal silicon wafer in asubstantially rectangular shape, in the vicinity where the ink supplypaths 11 (FIG. 3A) are to be formed. Note that, any one of the formationof the substrate 13 and the lamination of the heating resistor elements4 and the like may be performed prior to the other.

Subsequently, as illustrated in FIG. 4B, the recesses 9 are formed inthe second surface 13 b in the supply path formation region 14, and asillustrated in FIG. 4C, the second surface 13 b is covered with amaterial for the heat-radiation member 8 under a state in which thematerial for the heat radiation member 8 fills the recesses 9. Byforming the heat radiation member 8 in this manner, the heat radiationmember 8 having the protrusions 10 with a shape corresponding to theshape of the recesses 9 can be obtained relatively easily.

Next, as illustrated in FIGS. 4D and 4E, the ink supply paths 11 areformed. First, the heat radiation member 8 and the substrate 13 in theregion where the ink supply paths 11 are to be formed are removed toform the ink supply paths 11.

Depending upon the shape of the ink supply paths 11, the fluidresistance which ink receives when flowing through the ink supply paths11 may have a larger effect. Therefore, it is desired that the inksupply paths 11 be formed with relatively higher accuracy, and it oftentakes a relatively longer period of time for forming the ink supplypaths 11.

Meanwhile, the removal of the single crystal silicon wafer in order toform the supply path formation region 14 of the substrate 13 thin has asmall effect on ink, and hence, does not require high accuracy. That is,the supply path formation region 14 of the substrate 13 can be formedthin in a period of time shorter than that for forming the ink supplypaths 11.

Thus, by forming the supply path formation region 14 of the substrate 13thin, the ink supply paths 11 can be formed in a period of time shorterthan that in a case of forming the ink supply paths 11 without formingthe supply path formation region 14 thin.

Subsequently, as illustrated in FIG. 4F, the mold (FIG. 4A) is removedto form the ink flow path 7 and the nozzles 5. The ink jet recordinghead 1 is completed by being separated into each chip shape from thesingle crystal silicon wafer with a dicer, if required.

Third Embodiment

Next, an ink jet recording head according to a third embodiment of thepresent invention is described with reference to FIGS. 5A and 5B. FIGS.5A and 5B are cross-sectional views of the ink jet recording headaccording to this embodiment. Description of the same components asthose of the first embodiment is omitted.

As illustrated in FIG. 5A, the ink jet recording head 1 includes the inkejection portion 2, the substrate 3, and the heat radiation member 8.Further, in the ink jet recording head 1, the ink supply paths 11passing through the substrate 3 are formed so as to be surrounded by theheat radiation member 8 and the protrusions 10.

FIG. 5A is a cross-sectional view taken along line 5A-5A in FIG. 5Bperpendicularly crossing the first surface 3 a of the substrate 3 onwhich the ink ejection portion 2 is provided. FIG. 5B is across-sectional view taken along line 5B-5B in FIG. 5A parallel to thefirst surface 3 a of the substrate 3.

As illustrated in FIGS. 5A and 5B, in the ink jet recording head 1 ofthis embodiment, the ink supply paths 11 are formed so as to besurrounded by the protrusions 10. By forming the ink supply paths 11 inthis manner, the proportion of the path of each of the ink supply paths11 surrounded by the heat radiation member 8 with respect to the totalpath of each of the ink supply paths 11 is increased.

A single crystal silicon wafer is often used for the substrate 3, and ametal such as Au is often used for the heat radiation member 8. A metalsuch as Au is removed sufficiently slowly in dry etching compared withthe single crystal silicon wafer. Therefore, when the heat radiationmember 8 and the protrusions 10 are formed of a metal such as Au, thesubstrate 3 can be processed by dry etching, using the heat radiationmember 8 and the protrusions 10 as an etching mask. Thus, compared withthe case of processing the substrate 3 by dry etching using only theheat radiation member 8 as the etching mask, the dimension stability ofthe ink supply paths 11 is enhanced.

Further, in a case of dry etching using ions, the heat radiation member8 and the protrusions 10 block ions that do not enter in parallel to adirection along the path of the ink supply paths 11 with the use of theradiation member 8 and the protrusions 10 as the etching mask.Therefore, the ink supply paths 11 can be formed with high accuracy. Atthis time, as openings of the ink supply paths 11 are narrower, the heatradiation member 8 and the protrusions 10 block the ions moreeffectively, and hence the ink supply paths 11 can be formed with higheraccuracy.

Accordingly, by increasing the proportion of the path of each of the inksupply paths 11 surrounded by the heat radiation member 8 and theprotrusions 10, the ink jet recording head 1 including the ink supplypaths 11 formed with higher accuracy can be obtained. As a result, inkcan be stably supplied to the ink ejection portion 2, and an image withhigher quality can be recorded at a higher speed.

REFERENCE SIGNS LIST

-   1 ink jet recording head-   2 ink ejection portion-   3 substrate-   8 heat radiation member-   9 recess-   10 protrusion-   11 ink supply path

According to the present invention, the ink jet recording head having ahigher heat radiation property, and the method of producing the ink jetrecording head can be provided.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2011-020785, filed Feb. 2, 2011, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An ink jet recording head, comprising: an inkejection portion, in which heat is applied to ink supplied insidethereof, thereby providing the ink with a pressure for ejecting the inkoutside; a substrate having a first surface on which the ink ejectionportion is provided and a second surface on an opposite side to thefirst surface, the second surface having at least one recess; and a heatradiation member for releasing heat outside, the heat being transmittedfrom the ink ejection portion to the substrate, the heat radiationmember having a protrusion with a shape corresponding to a shape of theat least one recess, the protrusion being embedded in the at least onerecess so that the protrusion is provided in direct contact with the atleast one recess.
 2. The ink jet recording head according to claim 1,further comprising an ink supply path for supplying ink from an outsidethereof, the ink supply path being formed of a through-hole passingthrough the substrate and the heat radiation member.
 3. The ink jetrecording head according to claim 2, wherein: the substrate includes asupply path formation region in which the ink supply path is formed anda supply path non-formation region other than the supply path formationregion, the supply path formation region having a dimension in adirection along the ink supply path smaller than a dimension of thesupply path non-formation region in the direction; and the at least onerecess is formed at least in the second surface in the supply pathformation region.
 4. The ink jet recording head according to claim 2,wherein the heat radiation member has a material by which thethrough-hole is formable with a higher accuracy compared with a case ofthe substrate, and the ink supply path is formed so as to be surroundedby the protrusion of the heat radiation member.
 5. The ink jet recordinghead according to claim 1, wherein the heat radiation member comprisesany one metal of Au, Ta, Pt and Ir, or an alloy made of at least two ofAu, Ta, Pt and Ir.
 6. A method of producing an ink jet recording headincluding an ink ejection portion, in which heat is applied to inksupplied inside thereof, thereby providing the ink with a pressure forejecting the ink outside; a substrate having a first surface on whichthe ink ejection portion is provided and a second surface on an oppositeside to the first surface, the second surface having at least onerecess; and a heat radiation member for releasing heat outside, the heatbeing transmitted from the ink ejection portion to the substrate, theheat radiation member having a protrusion with a shape corresponding toa shape of the at least one recess, the protrusion being embedded in theat least one recess so that the protrusion is provided in direct contactwith the at least one recess, the method comprising: a step of formingthe at least one recess in the second surface of the substrate; and astep of forming the heat radiation member so that the heat radiationmember covers the second surface under a state in which a material forthe heat radiation member fills the at least one recess.
 7. The methodof producing an ink jet recording head according to claim 6, the ink jetrecording head further including an ink supply path for supplying inkfrom an outside thereof to the ink ejection portion, the ink supply pathbeing formed of a through-hole passing through the substrate and theheat radiation member, the method further comprising: a step of removinga part of the heat radiation member formed in the heat radiation memberforming step, corresponding to the ink supply path, to expose the secondsurface; and a step of removing the substrate in a part corresponding tothe ink supply path from the exposed second surface by etching, with aremaining part of the heat radiation member being used as an etchingmask, to form the ink supply path.
 8. The method of producing an ink jetrecording head according to claim 7, the inkjet recording beingconfigured so that the substrate includes a supply path formation regionin which the ink supply path is formed and a supply path non-formationregion other than the supply path formation region, the supply pathformation region having a dimension in a direction along the ink supplypath smaller than a dimension of the supply path non-formation region inthe direction; and the recess is formed at least in the second surfacein the supply path formation region, the method further comprising astep of partially removing the supply path formation region of thesubstrate prior to the recess forming step, thereby making the supplypath formation region thinner than the supply path non-formation region,wherein the recess forming step comprises forming the recess at least inthe second surface in the supply path formation region.